Automotive vehicles have doors, lift gates and other closures that are commonly equipped with a window. In many instances the window is moveable to provide an open passage between the vehicle interior and the vehicle exterior. Moveable windows often slide up and down between a raised closed position and a lowered open position where the window is at least partially stored in the vehicle door, lift gate or other closure.
Several types of window regulator mechanisms are now used to raise and lower the window. Known mechanisms include cross arm mechanisms, single arm mechanisms, cable mechanisms and tape mechanisms.
U.S. Pat. No. 4,672,771 granted to Michael K. Lam et al on Jun. 16, 1987 and U.S. Pat. No. 4,839,990 granted to Michael K. Lam et al on Jun. 20, 1989 disclose typical tape drive mechanisms. The typical tape drive mechanism generally comprises a flat plastic drive tape that is fitted around a sprocket wheel and the tape has spaced transverse apertures or other conformations that cooperate with the sprocket wheel to drive the tape.
While such tape drive mechanisms have been used successfully in the past, the mechanisms have a draw back in that the tape travels inside the closure with its width oriented perpendicular to the length of the closure. The middle and lower portions of the closures are generally wide enough to accommodate the width of the tape. However there are often space limitations at the window sill area which is preferably as thin as possible for ascetic and other reasons. In the past, the space problem has been solved by stopping the window sash plate well below the window sill. This solution is not entirely satisfactory because, the door height must be increased to store the window in the open or down position which inhibits design freedom.
Another drawback of known tape drive mechanism of the type discussed above is that the tape pushes the window in one direction, usually down, and pulls the window in the other direction, usually up. Since the tape acts in compression as well as in tension, the tape is thick as well as wide in order to handle the compressive loads. This decreases the flexibility of the tape and inhibits routing the tape inside the vehicle door.
Furthermore, the tape is often routed through tape channels that follow the curvature of the windows. These curved tape channels edge bend the tape resulting in high frictional resistence when the tape is pushed through the tape channel. Thus, systems requiring curved tape channels are very inefficient because large drive motors or considerable manual effort is required to move the window in one direction, usually down.